The broad long-term objectives of this project are to: 1) determine how cleft lip/palate and its management affect nasal airway patency and breathing behaviors and 2) assess the biological, morphological and behavioral consequences of nasal airway impairment. The specific aims of this application are to: a) Determine on a longitudinal basis how patency of the nasal airway and breathing behaviors are affected by growth as well as physical management of cleft lip and palate. b) Determine the sensitivity of the respiratory system for detecting changes in nasal airway resistance. c) Determine how cleft lip and palate and associated nasal airway impairment affect the sensitivity of the detection system. d) Determine the effects of cleft lip/palate on the sensory and motor mechanisms that underlie the interactions between breathing and olfaction. Four instrumental approaches will be used in these studies. They include: 1) Pressure-flow studies to measure nasal cross-sectional area and nasal airway resistance; 2) Inductive plethysmography to measure oral and nasal breathing (respiratory mode); 3) Instrumentation for studying the sensitivity of the respiratory detection system; 4) Customized, computerized olfactometer and respiratory monitoring system to deliver odorants/irritants and record respiratory and behavioral responses. This research involves several new approaches for studying respiratory behaviors and olfactory performance in the cleft lip/palate population. The longitudinal studies are expected to provide clinically relevant information on the immediate and long-term effects of growth and physical management of cleft lip/palate. Additionally, these studies concern breathing as a regulating system phenomenon, an area that appears promising in terms of understanding how the body responds morphologically and physiologically to airway impairment. Finally, this research should provide new information on how cleft lip/palate affects olfactory performance, an area that has been neglected despite the importance of this major sensory system.